OPERA = navigator.userAgent.indexOf("Opera") > -1 ? 1 : 0;

function insertTag(obj, stag, etag)
{
	if (navigator.userAgent.indexOf("MSIE") > -1 || OPERA) {
		insertTagIE(obj, stag, etag);
	} else if (window.getSelection && navigator.userAgent.indexOf("Safari") == -1) {
		insertTagMoz(obj, stag, etag);
	} else {
		insertTagNS(obj, stag, etag);
	}
}

function insertTagNS(obj, stag, etag)
{
	obj.value = obj.value+stag+etag;
}

function insertTagMoz(obj, stag, etag)
{
	txt = window.getSelection();

	if (!txt || txt == '') {
		t = document.getElementById('txtb');
		h = document.getElementsByTagName('textarea')[0];
		if (t.selectionStart == t.selectionEnd) {
			t.value = t.value.substring(0, t.selectionStart) + stag + etag +  t.value.substring(t.selectionEnd, t.value.length);
			return;
		}
		txt = t.value.substring(t.selectionStart, t.selectionEnd);
		if (txt) {
			t.value = t.value.substring(0, t.selectionStart) + stag + txt + etag +  t.value.substring(t.selectionEnd, t.value.length);
			return;
		}
	}
	obj.value = obj.value+stag+etag;
}

function insertTagIE(obj, stag, etag)
{
	r=document.selection.createRange();
	if( document.selection.type == 'Text' && (obj.value.indexOf(r.text) != -1) ) {
		a = r.text;
		r.text = stag+r.text+etag;
		if ( obj.value.indexOf(document.selection.createRange().text) == -1 ) {
			document.selection.createRange().text = a;
		}
	}
	else insertAtCaret(obj, stag+etag);	
}

function insertAtCaret(textEl, text)
{
	if (textEl.createTextRange && textEl.caretPos)
	{
		var caretPos = textEl.caretPos;
		caretPos.text = caretPos.text.charAt(caretPos.text.length - 1) == ' ' ? text + ' ' : text;
	}
	else
		textEl.value  =  textEl.value + text;
}